The present application relates to aspect ratio trapping (ART), and more particularly to the formation of narrow ART trench structures for heteroepitaxy.
Heteroepitaxy is the process of epitaxially growing one semiconductor material on another. Since the crystal structures of two semiconductor materials are usually different, issues can arise involving lattice mismatch between the different crystal structures. These differences are responsible for the formation of dislocation defects. ART has been developed to enable heteroepitaxial growth with reduced defect density. For fin field effect transistors (FinFETs), fins formed by heteroepitaxy typically require formation of ART trenches at fin dimensions (typically with a width around 12 nm or less). However, forming ART trenches at such small fin dimensions is very challenging.